The present invention relates to a feeding apparatus, and more particularly to a feeding apparatus which is able to restrain a yawing motion of a movable body, which is elongated in the direction at a right angle to the moving direction thereof, with a simple mechanism.
An example of the conventional feeding apparatus is disclosed in Unexamined Japanese Patent Publication No. Hei. 5-92376. The feeding apparatus, as shown in FIG. 15, is a two-dimensional motion mechanism formed of various components assembled onto a base 100. In the feeding apparatus, a pair of X-axis guides 114a and 114b are arranged in parallel while being extended in the X-axial direction. A pair of Y-axis guides 126a and 126b are arranged in parallel while being extended in the direction at an angle to the X-axis direction. An X-axis slider guide 130 is disposed between the Y-axis guides 126a and 126b while being extended in the X-axis direction, and is movable along the Y-axis guides 126a and 126b in the Y-axis direction. A Y-axis slider guide 118 is arrayed between the X-axis guides 114a and 114b while being extended in the Y-axis direction, and is movable along the X-axis guides 114a and 114b in the X-axis direction.
A slider 142 is movable in the X- and Y-axis directions while being guided by the X-axis slider guide 130 and the Y-axis slider guide 118. Drive mechanisms 134, 136, 138 and 140 are provided for moving the slider 142 in the X- and Y-axis directions. An X-axis restraining device is mounted for restraining a slant of the X-axis slider guide 130 to the X-axis direction. A Y-axis restraining device is mounted for restraining a slant of the Y-axis slider guide 118 to the Y-axis direction.
The X-axis restraining device includes X-axis racks 112a and 112b, a Y-axis rod 120, and pinion gears 122a and 122b mounted at both ends of the rod. The Y-axis restraining device includes Y-axis racks 124a and 124b, an X-axis rod 132, and pinion gears 133a and 133b mounted on both ends of the rod. Those restraining devices restrain angular displacements of the slider 142 in the yawing direction when it is moved in the X- and Y-axis directions while being guided by the X-axis rod 132 and the Y-axis rod 120.
The two-dimensional motion mechanism as the conventional feeding apparatus has the following disadvantages:
1) Heavy members are used for the Y-axis rod 120 of the Y-axis restraining device and the X-axis rod 132 of the X-axis restraining device. The inertia of those heavy members forms an additional load to the drive mechanism. PA0 2) The mechanism is complicated, and requires a large number of the component parts. This leads to increase of the cost to manufacture. PA0 3) If flat belts, wires or the like are used in place of the rack-pinion mechanism or the timing belts for restraining angular displacements of the Y-axis rod 120 of the Y-axis restraining device and the X-axis rod 132 of the X-axis restraining device, then a slip of those rods 132 and 120 occurs. In this state, the drive force is improperly transmitted.